This invention relates generally to a key operated tumbler lock and, more particularly, to a high security lock highly resistant to the picking techniques normally employed to violate tumbler locks.
As is well known in the lock industry, most tumbler locks are quite susceptible to violation by persons skilled in picking techniques. In most instances, a picker employs the sense of feel to sequentially move individual tumblers to their shear positions while maintaining tension on a movable portion on a lock. Because of efforts to complicate the steps required to breach security, locks of varying configuration and with diverse operational characteristics have been developed. One of the best known and most inviolate commercially available lock is the so-called Medeco cylinder lock disclosed in U.S. Pat. No. 3,499,302. That lock employs a key specially bitted with V-shaped cuts that both elevate and rotate pin tumblers into shear positions that entail a predetermined positioning of pin tumblers both longitudinally and angularly within their pinways. Although providing a high degree of security, the Medeco lock does suffer from one disadvantage. Because the individual pins possess ridges that mate with the V-shaped notches in the key and establish pin elevation, they are far more susceptible to wear than are the relatively smooth surfaced pins employed in conventional cylinder locks. Such wear can ultimately degrade or even prevent normal use of a lock with a properly bitted key.
The object of this invention, therefore, is to provide an improved key operated tumbler lock that is highly resistant to picking and is less susceptible to wear than prior high security locks.